The immunogenetics of the HLA complex were exhaustively studied equals HLA-C locus, interlocus antigen (shared between HLA-A and B), Ia-like antigens. A first B lymphocyte system, Ly-Li, was described and localized in the HLA-D region. The relationship between the Li antigens and the HLA-D products was precised. The best correlation was observed with the PLT test, which was first applied in man in this laboratory. Another B-lymphocyte system (Ly-lo) independent from HLA was also further studied, as well as other immuno-genetic systems as the Atri system on A-lymphocytes. Several studies were conducted on transplantation using bone marrow grafts performed by our team for aplastic anemia or leukemia. BIBLIOGRAPHIC REFERENCES: Pierres, M., Legrand, L., Lepage, V. and Dausset, J. Joint Report of the B Lymphocyte Specifities Workshop on the France One Region. Tissue Antigens, 1976, 8, 345-353. Margelli-Barge, A., J.C. Poirer, Benjam, A. and Dausset, J. A Lymphocyte Immunogenetic System, Atri, associated with the ABO Blood Group and the ABH Secretor System. Vox. Sang., 1976, 30, 81-90.